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[PATCH v2 10/13] perf record: Lazy load kernel symbols

Ian Rogers posted 13 patches 2 years, 2 months ago
There is a newer version of this series
[PATCH v2 10/13] perf record: Lazy load kernel symbols
Posted by Ian Rogers 2 years, 2 months ago 
Commit 5b7ba82a7591 ("perf symbols: Load kernel maps before using")
changed it so that loading a kernel dso would cause the symbols for
the dso to be eagerly loaded. For perf record this is overhead as the
symbols won't be used. Add a symbol_conf to control the behavior and
disable it for perf record and perf inject.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-inject.c   | 4 ++++
 tools/perf/builtin-record.c   | 2 ++
 tools/perf/util/event.c       | 4 ++--
 tools/perf/util/symbol_conf.h | 3 ++-
 4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index c8cf2fdd9cff..1539fb18c749 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -2265,6 +2265,10 @@ int cmd_inject(int argc, const char **argv)
 		"perf inject [<options>]",
 		NULL
 	};
+
+	/* Disable eager loading of kernel symbols that adds overhead to perf inject. */
+	symbol_conf.lazy_load_kernel_maps = true;
+
 #ifndef HAVE_JITDUMP
 	set_option_nobuild(options, 'j', "jit", "NO_LIBELF=1", true);
 #endif
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index dcf288a4fb9a..8ec818568662 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3989,6 +3989,8 @@ int cmd_record(int argc, const char **argv)
 # undef set_nobuild
 #endif
 
+	/* Disable eager loading of kernel symbols that adds overhead to perf record. */
+	symbol_conf.lazy_load_kernel_maps = true;
 	rec->opts.affinity = PERF_AFFINITY_SYS;
 
 	rec->evlist = evlist__new();
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 923c0fb15122..68f45e9e63b6 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -617,13 +617,13 @@ struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr,
 	if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) {
 		al->level = 'k';
 		maps = machine__kernel_maps(machine);
-		load_map = true;
+		load_map = !symbol_conf.lazy_load_kernel_maps;
 	} else if (cpumode == PERF_RECORD_MISC_USER && perf_host) {
 		al->level = '.';
 	} else if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) {
 		al->level = 'g';
 		maps = machine__kernel_maps(machine);
-		load_map = true;
+		load_map = !symbol_conf.lazy_load_kernel_maps;
 	} else if (cpumode == PERF_RECORD_MISC_GUEST_USER && perf_guest) {
 		al->level = 'u';
 	} else {
diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
index 0b589570d1d0..2b2fb9e224b0 100644
--- a/tools/perf/util/symbol_conf.h
+++ b/tools/perf/util/symbol_conf.h
@@ -42,7 +42,8 @@ struct symbol_conf {
 			inline_name,
 			disable_add2line_warn,
 			buildid_mmap2,
-			guest_code;
+			guest_code,
+			lazy_load_kernel_maps;
 	const char	*vmlinux_name,
 			*kallsyms_name,
 			*source_prefix,
-- 
2.42.0.609.gbb76f46606-goog
Re: [PATCH v2 10/13] perf record: Lazy load kernel symbols
Posted by Adrian Hunter 2 years, 2 months ago 
On 12/10/23 09:23, Ian Rogers wrote:
> Commit 5b7ba82a7591 ("perf symbols: Load kernel maps before using")
> changed it so that loading a kernel dso would cause the symbols for
> the dso to be eagerly loaded. For perf record this is overhead as the
> symbols won't be used. Add a symbol_conf to control the behavior and
> disable it for perf record and perf inject.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/builtin-inject.c   | 4 ++++
>  tools/perf/builtin-record.c   | 2 ++
>  tools/perf/util/event.c       | 4 ++--
>  tools/perf/util/symbol_conf.h | 3 ++-
>  4 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index c8cf2fdd9cff..1539fb18c749 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -2265,6 +2265,10 @@ int cmd_inject(int argc, const char **argv)
>  		"perf inject [<options>]",
>  		NULL
>  	};
> +
> +	/* Disable eager loading of kernel symbols that adds overhead to perf inject. */
> +	symbol_conf.lazy_load_kernel_maps = true;

Possibly not for itrace kernel decoding, so:

	if (!inject->itrace_synth_opts.set)
		symbol_conf.lazy_load_kernel_maps = true;

> +
>  #ifndef HAVE_JITDUMP
>  	set_option_nobuild(options, 'j', "jit", "NO_LIBELF=1", true);
>  #endif
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index dcf288a4fb9a..8ec818568662 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -3989,6 +3989,8 @@ int cmd_record(int argc, const char **argv)
>  # undef set_nobuild
>  #endif
>  
> +	/* Disable eager loading of kernel symbols that adds overhead to perf record. */
> +	symbol_conf.lazy_load_kernel_maps = true;
>  	rec->opts.affinity = PERF_AFFINITY_SYS;
>  
>  	rec->evlist = evlist__new();
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 923c0fb15122..68f45e9e63b6 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -617,13 +617,13 @@ struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr,
>  	if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) {
>  		al->level = 'k';
>  		maps = machine__kernel_maps(machine);
> -		load_map = true;
> +		load_map = !symbol_conf.lazy_load_kernel_maps;
>  	} else if (cpumode == PERF_RECORD_MISC_USER && perf_host) {
>  		al->level = '.';
>  	} else if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) {
>  		al->level = 'g';
>  		maps = machine__kernel_maps(machine);
> -		load_map = true;
> +		load_map = !symbol_conf.lazy_load_kernel_maps;
>  	} else if (cpumode == PERF_RECORD_MISC_GUEST_USER && perf_guest) {
>  		al->level = 'u';
>  	} else {
> diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
> index 0b589570d1d0..2b2fb9e224b0 100644
> --- a/tools/perf/util/symbol_conf.h
> +++ b/tools/perf/util/symbol_conf.h
> @@ -42,7 +42,8 @@ struct symbol_conf {
>  			inline_name,
>  			disable_add2line_warn,
>  			buildid_mmap2,
> -			guest_code;
> +			guest_code,
> +			lazy_load_kernel_maps;
>  	const char	*vmlinux_name,
>  			*kallsyms_name,
>  			*source_prefix,
Re: [PATCH v2 10/13] perf record: Lazy load kernel symbols
Posted by Ian Rogers 2 years, 1 month ago 
On Thu, Oct 19, 2023 at 4:02 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 12/10/23 09:23, Ian Rogers wrote:
> > Commit 5b7ba82a7591 ("perf symbols: Load kernel maps before using")
> > changed it so that loading a kernel dso would cause the symbols for
> > the dso to be eagerly loaded. For perf record this is overhead as the
> > symbols won't be used. Add a symbol_conf to control the behavior and
> > disable it for perf record and perf inject.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/builtin-inject.c   | 4 ++++
> >  tools/perf/builtin-record.c   | 2 ++
> >  tools/perf/util/event.c       | 4 ++--
> >  tools/perf/util/symbol_conf.h | 3 ++-
> >  4 files changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> > index c8cf2fdd9cff..1539fb18c749 100644
> > --- a/tools/perf/builtin-inject.c
> > +++ b/tools/perf/builtin-inject.c
> > @@ -2265,6 +2265,10 @@ int cmd_inject(int argc, const char **argv)
> >               "perf inject [<options>]",
> >               NULL
> >       };
> > +
> > +     /* Disable eager loading of kernel symbols that adds overhead to perf inject. */
> > +     symbol_conf.lazy_load_kernel_maps = true;
>
> Possibly not for itrace kernel decoding, so:
>
>         if (!inject->itrace_synth_opts.set)
>                 symbol_conf.lazy_load_kernel_maps = true;

Thanks, added to v3.

Ian

> > +
> >  #ifndef HAVE_JITDUMP
> >       set_option_nobuild(options, 'j', "jit", "NO_LIBELF=1", true);
> >  #endif
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index dcf288a4fb9a..8ec818568662 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -3989,6 +3989,8 @@ int cmd_record(int argc, const char **argv)
> >  # undef set_nobuild
> >  #endif
> >
> > +     /* Disable eager loading of kernel symbols that adds overhead to perf record. */
> > +     symbol_conf.lazy_load_kernel_maps = true;
> >       rec->opts.affinity = PERF_AFFINITY_SYS;
> >
> >       rec->evlist = evlist__new();
> > diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> > index 923c0fb15122..68f45e9e63b6 100644
> > --- a/tools/perf/util/event.c
> > +++ b/tools/perf/util/event.c
> > @@ -617,13 +617,13 @@ struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr,
> >       if (cpumode == PERF_RECORD_MISC_KERNEL && perf_host) {
> >               al->level = 'k';
> >               maps = machine__kernel_maps(machine);
> > -             load_map = true;
> > +             load_map = !symbol_conf.lazy_load_kernel_maps;
> >       } else if (cpumode == PERF_RECORD_MISC_USER && perf_host) {
> >               al->level = '.';
> >       } else if (cpumode == PERF_RECORD_MISC_GUEST_KERNEL && perf_guest) {
> >               al->level = 'g';
> >               maps = machine__kernel_maps(machine);
> > -             load_map = true;
> > +             load_map = !symbol_conf.lazy_load_kernel_maps;
> >       } else if (cpumode == PERF_RECORD_MISC_GUEST_USER && perf_guest) {
> >               al->level = 'u';
> >       } else {
> > diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
> > index 0b589570d1d0..2b2fb9e224b0 100644
> > --- a/tools/perf/util/symbol_conf.h
> > +++ b/tools/perf/util/symbol_conf.h
> > @@ -42,7 +42,8 @@ struct symbol_conf {
> >                       inline_name,
> >                       disable_add2line_warn,
> >                       buildid_mmap2,
> > -                     guest_code;
> > +                     guest_code,
> > +                     lazy_load_kernel_maps;
> >       const char      *vmlinux_name,
> >                       *kallsyms_name,
> >                       *source_prefix,
>

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